Water jet method of deslagging a metal surface



1964 I. P. THOMPSON ETAL 3,163,559

WATER JET METHOD OF DESLAGGING A METAL SURFACE Original Filed Nov. 12,1957 FIG. I

SCARF ING MACHINE CHUTE INVENTORS IVAN P. THOMPSON EDWARD H. HOUSTED kwWM,

ATTORNEY United States. Patent ,7

3,163,559 WATER JET METHOD OF DESLAGGING A METAL SURFACE Ivan P.Thompson, Hillside, and Edward H. Monsted,

Garwood, N.J., assignors to Union Carbide Corporation, a corporation ofNew York Original applications Nov. 12, 1957, Ser. No. 695,846, and Feb.25, 1960, Ser. No. 11,947, now Patent No. 3,062,456, dated Nov. 6, 1962.Divided and this application Sept. 17, 1962, Ser. No. 224,183

1 Claim. (Cl. 13434) This invention relates to a process for removingthe slag and waste products from thermochemically desurfaced metalslabs. V

The metal shapes produced by steel mills customarily have surfacedefects which it is desirable to remove. This removal is most commonlyaccomplished by a thermochemically desurfacing method known as scarfingWhich consists of projecting on such surfaces a voluminous oxygen streamaccompanied by burning oxy-fuel-gas streams to convert the surface'toapartially oxidized molten product or slag. The resultant slag must thenbe removed so that a clean surface will result. One common means forremoving the resultant slag from the desurfaced slab is by high pressurewater jets. When sufficiently high pressure jets are used, the slag isgranulated and washed away leaving a cleaned billet, free of surfacedefects.

In recent years, scarfing machines have been developed which are capableof handling slabs of widely divergent sizes and shapes. It soon becameapparent that conventional water jet configurations were incapable ofperforming efficiently with all slab sizes. During desurfacing of thenarrower slabs, for instance, the nozzle producing the horizontal waterjet may be over three feet from the near edge of the slab. Previouslyemployed water nozzles produced streams which are incapable ofeffectively skimming the slab from such a distance. Further, divergenceof the stream not only decreases the available force of the jet at thesurface of the slab but causes some Water to strike the edge of the slabwith the possible development of an undesirable black spot due to unevenchilling. The diverging stream also causes both water and slag tospatter onto the desurfacing machine and onto the desurfacing reactionarea, thus creating mechanical and electrical difficulties in themachine itself as well as interfering with the reaction of thedesurfacing process.

It is a primary object of the present invention to provide a moreefiicient method of disposing of the slag created by-norrnal steel milldesurfacing procedures.

It is a further object of the present invention to provide a method ofdisposing of slag capable of more exact control of the point ofimpingement of the water jet on a surface. V

It is a further object of the present invention to provide a method ofdisposing of slag using a high pressure water stream which willsubstantially reduce uncontrollable spatter of solid particles and-Water in undesirable directions. I I

It is a further object of the present invention to provide a Water jetcapable of imparting a substantially constant impact pressure to asurface at various distances from the nozzle.

Other objects, features and advantages of the present invention willbecome apparent from the following detailed description taken inconjunction with the accompanying drawings wherein: V i

In accordance with these objects an invention is provided in the waterjet method of deslagging a surface of a metal slab subsequent to saidslab being thermally 3 ,163,559 Patented Dec. 29, 1964 treated byimpinging thereon an oxy-fuel-gas flow to form said slag, theimprovement therewith which comprises, forming a flow of fluid underpressure through a conduit, forming said flow into a high pressurehollow stream having a substantially constant outer diameter anddirecting said constant diameter stream tangentially along said surfaceto contact the slag formed thereon while minimizing contact of thestream with the slab surface whereby said slag is carried from saidsurface.

The use of a hollow, constant diameter stream results in a moreeflicient and complete removal of slag from the slab. The drawings showapparatus which gives a hollow constant diameter stream. Other types ofapp-aratus, not shown, will also give the hollow stream needed for theprocess of this invention. The hollow, constant diameter streams moreefficiently skim the surface of a scarfed slab removing the slag formedthereon by a desurfacing operation. Whereas diverging, solid water jetsused before tend to splatter over the surface of the slab sending slagand Water in all directions, the hollow, constant diameter stream hasthe necessary stability and lack of turbulence required to efiectexcellent slag granulation and removal. Such results are not achieved bymerely increasing the velocity of the stream, but are achieved here bythe use of the hollow water stream.

In the drawings: 7

FIG; 1 is an illustration in perspective of a nozzle in position toremove the slag produced by a scarfing machine;

FIG. 2 is a side view showing the jet produced;

FIG. 3 is a view of a longitudinal section through a nozzle capable ofuse in the process of this invention indicating the internalconstruction of the nozzle and the manner in which the water jet isformed;

FIGS. 4-6 are end cross sectional views'taken on lines 44, 5-5, and 66as shown in FIG. 3; and

FIG. 7 is an exploded perspective view of the core and one fin, showingthe manner of construction.

With reference to FIG. 3, it will be seen that nozzle 2 comprises anouter tube or cylinder 4, an inner conical core 6 in axial alignmentwith the tube 4 and held in fixed position by a multiplicity of radialfins 8.

The cone 6 is positioned in such a manner that its small end isupstream. Fins 8 are tapered at both upstream and downstream ends tominimize disturbance of stream flow. The downstream end of aperture 14of the outer tube or sleeve lprojects slightly beyond the base of thecone 6 for the best results. This configuration results in a stream 10which initially converges some what upon departure from the nozzle toform a vena contracta 12 and then expands to a uniform diametersubstantially that of the nozzle. The distance between the aperture 14and the vena contracta 12 varies in proportion to the distance the outersleeve 4 projects beyond the inner cone 6. In one embodiment of theinven tion, the outer sleeve 4' is formed of two inch internal diametertubing and has alength of 11 inches. The

cone 6'is l1 inches long with a maximum diameter of 1 inches and issupported by three equi-angularly spaced supporting fins 8 to combinehigh maximum stability with minimum flow resistance and turbulence. Thedistance between the base of the cone 6 and the downstream end of sleeve4 is /2 inch. When formed with these dimensions and operated with aninlet pressure of about psi, the vena contracta occurs two feet from thenozzle. This stream produces no appreciable fanon over a distance of atleast eight feet frointhe nozzle. Furthermore, this nozzle produces astream of high velocity which elfects excellent slag granulation andremoval.

While one nozzle has been specifically described in connection with theprocess of this invention, it is to be understood that the invention isnot solimited in application and that other nozzles discharging hollow,constant diameter Water jets may be employed.

This application is a division of copending application Serial No.11,947, filed February 25, 1960 now Pat. No. 3,062,456, and abandonedapplication Serial No. 695,846, filed November 12, 1957.

What is claimed is:

In the water jet method of deslagging a surface of a metal slabsubsequent to said slab being thermally treated 10 by impinging thereonan oxy-fuel-gas flow to form said slag, the improvement therewith whichcomprises, forming a flow of fluid under pressure through a conduit,forming said flow into a high pressure hollow stream having asubstantially constant outer diameter and directing said constantdiameter stream tangentially along said surface to contact the slagformed thereon while minirnizing contact of the stream with the slabsurface whereby said slag is carried from said surface.

References Cited in the file of this patent UNITED STATES PATENTS

